A New Modulation Identification Scheme for OFDM in Multipath Rayleigh Fading Channel

Abstract

This paper applies wavelet transform (WT) on Orthogonal Frequency Division Multiplexing (OFDM) and single carrier (SC) digital signals twice (WT-T) to extract the transient characteristics of them, and then by using the transient characteristics in WT-T domain, it is easy to identify the two types of signals. The simulations show that the proposed identification algorithms can obtain good performances in low signal to noise ratio (SNR) and multipath Rayleigh fading channel. In addition, the effects of sample rate and symbol rate on the identification algorithms are analyzed and simulated. To obtain the best performances of the identification algorithms, sample rate is set to be equal to 2.4 times of carrier frequency approximately, therefor, the difference of characteristics between OFDM and SC signals reaches maximum, while OFDM and SC signals can be well separated if only the symbol rate is greater than 20 kHz.